FIG. 1 illustrates RNs (Relay Nodes) and user equipments (UEs) existing in a base station region in a wireless communication system. The relay node refers to a node configured to intermediately receive a signal transmitted from a source node and to wirelessly relaying the received signal to a destination node. The relay node may be considered for data transmission rate coverage enhancement of the user equipment (or user terminal), group mobility, temporary network positioning, throughput enhancement in cell boundary area, and/or coverage provision within a new area. The user equipment may directly communicate with the base station, or the user equipment may perform communication communication with the base station over 2 hops through the relay node.
The relay node transmits the data received from the base station to a user equipment, which is located (or positioned) within a relay node area, and the relay node may transmit data received from the user equipment, which is located (or positioned) within a relay node area, to the base station. And, for simplicity in the description, a wireless link between the base station and the relay node will be referred to as a backhaul link. A link from the base station to the relay node will be referred to as a backhaul downlink, and a link from the relay node to the base station will be referred to as a backhaul uplink. Additionally, a wireless link between the relay node and the user equipment will be referred to as an access link. And, a link from the relay node to the user equipment will be referred to as an access downlink, and a link from the user equipment to the relay node will be referred to as an access uplink.